A user has several exercises to choose from for exercising his calf muscles (known medically as the "gastrocnemius" muscles). These muscles are located on the back of the tibia and fibula bones of the lower leg.
Some of the presently available exercises are useful in exercising the calf, but present a risk of injury to other portions of the body. In one common exercise, for example, the exerciser stands with a heavily weighted bar or similar device on his shoulders. He then places the balls of his feet on a platform, allowing the heels of his feet to overhang an open space. The user raises his body up and down against the weight by moving his heels up and down using his his calf muscles.
The most serious drawback to this exercise is that a substantial amount of weight is supported by the user's back during the exercise. Further, as the calf muscles tire, users often raise and lower the bar by slumping and straightening their backs instead of solely using their calves. Back injuries are often the result.
One exercise which does not involve directly supporting the weight on the back is where a user sits and supports a bar across his knees. With the balls of his feet resting on a platform or other flat surface, the user exercises his calf muscles by raising his legs up and down. This exercise has several other drawbacks.
First, the user must support the narrow, heavy bar on his knees, which is often quite uncomfortable. The user must also move the bar onto, and off from, his knees. When a substantial amount of weight is involved, movement of the bar from a standing position to a seated position above the exerciser's knees is unstable and risky. When removing the bar while seated, the user grasps the bar and forces his body upwardly without the aid of his lower legs. In both maneuvers, the exerciser risks back and leg injuries.
Neither exercise allow for easy adjustment of the force against which the calves are exercised. For example, in the case of the second exercise, the user must place the bar back on the ground and add or subtract weights from the bar, and then place the bar back onto his knees before continuing.
Further, neither exercise allows a user to independently adjust the force against which each calf muscle exercises. In the first exercise, the weight supported on the shoulders is evenly distributed between the two legs. The same is true of the second exercise where the bar spans both knees. In many instances, a user wishes to exercise one of the calf muscles against a slightly different force than the other, or may even wish to exercise one calf muscle but not the other.